An antenna for mobile communication or satellite broadcasting requires a function to change a beam direction (referred to as “beam scanning” or “beam steering”). As the antenna having such a function (hereinafter referred to as a “scanned antenna”), a phased array antenna including antenna units is known. However, an existing phased array antenna is expensive and thus, has an obstacle for popularization as a consumer product. Particularly, as the number of antenna units increases, the cost rises considerably.
Therefore, a scanning antenna utilizing high dielectric anisotropy (birefringence) of a liquid crystal material (including nematic liquid crystal and polymer dispersed liquid crystal) has been proposed (PTL 1 to PTL 4 and NPL 1). Since a dielectric constant of a liquid crystal material has frequency dispersion, a dielectric constant in a frequency band for microwaves (may also be referred to as a “dielectric constant for microwaves”) is particularly denoted herein by a “dielectric constant M (εm)”.
PTL 3 and NPL 1 each describe an inexpensive scanning antenna that can be obtained by utilizing liquid crystal display device (hereinafter referred to as “LCD”) technology.